what is the difference between error and residual

What is the different between error and residual?

For the graph below, the distance from each data points to the fitted regression line is the residual or error?

Errors are the difference between the true regression line (which is typically unobservable) and the actual values of Y that fall around the line.

Residuals are estimates of errors. We observe them when we take the difference between the value of Y from our estimated regression line and the true Y value.